1. Field of the Invention
This invention generally relates to design based sampling and binning for yield critical defects.
2. Description of the Related Art
The following description and examples are not admitted to be prior art by virtue of their inclusion in this section.
An integrated circuit (IC) design may be developed using a method or system such as electronic design automation (EDA), computer aided design (CAD), and other IC design software. Such methods and systems may be used to generate the circuit pattern database from the IC design. The circuit pattern database includes data representing a plurality of layouts for various layers of the IC. Data in the circuit pattern database may be used to determine layouts for a plurality of reticles. A layout of a reticle generally includes a plurality of polygons that define features in a pattern on the reticle. Each reticle is used to fabricate one of the various layers of the IC. The layers of the IC may include, for example, a junction pattern in a semiconductor substrate, a gate dielectric pattern, a gate electrode pattern, a contact pattern in an interlevel dielectric, and an interconnect pattern on a metallization layer.
The term “design data” as used herein generally refers to the physical design (layout) of an IC and data derived from the physical design through complex simulation or simple geometric and Boolean operations.
Fabricating semiconductor devices such as logic and memory devices typically includes processing a substrate such as a semiconductor wafer using a large number of semiconductor fabrication processes to form various features and multiple levels of the semiconductor devices. For example, lithography is a semiconductor fabrication process that involves transferring a pattern from a reticle to a resist arranged on a semiconductor wafer. Additional examples of semiconductor fabrication processes include, but are not limited to, chemical-mechanical polishing (CMP), etch, deposition, and ion implantation. Multiple semiconductor devices may be fabricated in an arrangement on a single semiconductor wafer and then separated into individual semiconductor devices.
Inspection processes are used at various steps during a semiconductor manufacturing process to detect defects on wafers to promote higher yield in the manufacturing process and thus higher profits. Inspection has always been an important part of fabricating semiconductor devices such as ICs. However, as the dimensions of semiconductor devices decrease, inspection becomes even more important to the successful manufacture of acceptable semiconductor devices because smaller defects can cause the devices to fail.
As design rules shrink, however, semiconductor manufacturing processes may be operating closer to the limitations on the performance capability of the processes. In addition, smaller defects can have an impact on the electrical parameters of the device as the design rules shrink, which drives more sensitive inspections. Therefore, as design rules shrink, the population of potentially yield relevant defects detected by inspection grows dramatically, and the population of nuisance defects detected by inspection also increases dramatically. Therefore, more and more defects may be detected on the wafers, and correcting the processes to eliminate of the defects may be difficult and expensive.
In trying to maximize the sensitivity of the inspection system to capture subtle spatially systematic “design-for-manufacturability” (DFM) defects resulting from design and process interdependencies, the system may be overwhelmed by millions of events in non-critical areas such as CMP fill regions. Detecting such nuisance defects is disadvantageous for a number of reasons. For example, these nuisance events need to be filtered out of the inspection results by post-processing of the inspection data. In addition, nuisance event detection limits the ultimate achievable sensitivity of the inspection system for DFM applications. A high rate of nuisance defect data may also overload the run time data processing capacity of the inspection system thereby reducing throughput and/or causing the loss of data.
Accordingly, it would be advantageous to develop methods and/or systems for wafer inspection-related applications that do not have one or more of the disadvantages described above.